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Introduction

The changes that occur in the pharynx during sleep in patients with obstructive sleep apnea and hypopnea syndrome (OSAHS) are still a source of controversy. The identification and quantitation of the site of pharynx obstruction in patients with OSAHS can be beneficial for the choice of the most appropriate treatment . Several studies on patients with a diagnosis of OSAHS have attempted to identify the sites where a reduction or even obstruction of the pharynx may occur, especially at the level of the retropalatal and retrolingual region, but the results obtained have varied widely . Nasofibrolaryngoscopy permits a direct observation of the moving pharynx and has been used in some studies to assess the changes that occur in patients with OSAHS .

The pharynx is a variable space according to the function performed, and its narrowing cannot always be identified in awake patients. Thus, to identify a possible collapse of the pharynx, it is necessary to perform a functional evaluation with the patient lying down and sleeping . Croft and Pringle , in 1991, described upper airway endoscopy during induced sleep and concluded that this diagnostic method permits the examiner to better determine the anatomical area responsible for the production of snoring and the site(s) of narrowing and obstruction of the pharynx under conditions that approximate physiological sleep . Nasofibrolaryngoscopy under sedation is considered by some authors to be probably the best diagnostic method available for the identification of the specific site of pharynx obstruction in patients with OSAHS .

The difficulty in measuring the pharynx in an appropriate manner is largely because of the morphometric change caused by the position, respiration, and consciousness status of an individual. It has been established that patients with OSAHS have a smaller pharyngeal volume compared with apparently healthy individuals and to snorers . Several studies use subjective methods or maneuvers that try to simulate collapse of the pharynx to identify critical area(s) of obstruction, with no consensus about their shape and quantitation .

Although there are several proposals for the treatment of OSAHS, maxillomandibular advancement surgery (MMAS) is the one with a high rate of success . However, the changes in the pharynx due to MMAS have not been fully clarified. Morphometric modifications of the pharynx with stretching of soft parts, repositioning of the tongue, and a consequent increase in the lumen of the organ are known to occur, but there are doubts about the extent of these changes and about their maintenance according to the position and the consciousness state of the individual. An endoscopic morphometric study of the pharynx comparing pre- and postoperative MMAS data in patients with OSAHS of all degrees can reveal the real gain of the pharynx with the patient lying down or sitting or awake or sleeping. Thus, we propose here a new endoscopic method for the evaluation of the pharynx that could objectively quantify the modifications that occur.